added __file__ param to exec call

[apelliciari]

In this way it's available when the file is executed.

Obviously __file__ will not have the path of the original script uploaded through wooey's addscript, but it allows compatibility if the standalone file is using it. Besides, it provides a way to extract the project path directly from the script

[coveralls]

Coverage remained the same at 33.208% when pulling 545b00aebf46fa9ae48c58f2a26128bfc368807f on apelliciari:master into 22dfed89c22d4d5a2446713c21b78b818365774c on wooey:master.

[Chris7]

Thanks @apelliciari. I don't have any issues with this, but I am wondering what the circumstances are that require it. Could you elaborate why this is needed for your setup?

[apelliciari]

In my case, for two reasons:

• I've a script that depends on local libraries. I need to add local libraries on the path to import them, but I don't want to put absolute paths inside the file. So, i search for the project name inside __file__ and build the project path. In this way i keep it relative
• the other reason is similar: I need to save some output files, and I want to save them in the project but with wooey I have no references.

I've done these modifications because my scripts were running correctly in the cli. I know that they aren't really "standalone" scripts, so this can be an edge case